Subject & Preheader

Remember: your headlines and preheaders will determine whether or not your emails will be opened.

On average, optimal length for email subject lines is around 60-70 characters, no more.

You could try to tweak several parameters for your subject lines, including:

Word order (try reversing the order)

Tone (neutral, friendly, provocative)

Length (try shorter, try longer)

Personalization (try including their first name)

When it comes to preheaders, they’re usually pulled from the first line of your email. But as your email marketing senses sharpen, you could try to create intentional preheaders that most emailing tools now support.

If you can create your own preheaders, try to write complementary information and add relevant words that could trigger your prospects’ curiosity.

Different days and hours

For various reasons, email campaigns don’t perform the same depending on when you send them.

For starters, you could try to send emails on different days of the week: GetResponse reports that Tuesdays get the best open rates compared to the rest of the week, although the gap is relatively small (19.9% for Tuesdays compared to 16.9 on Saturdays).

Because studies can be biased and cultural differences can change this data, it’s important that you try different days in order to find what works best for your company.

Likewise, there are studies like MailChimp’s and HubSpot’s that tend to show a particular trend for optimal sending time around 10am to 11am.

Similarly to body length, visuals won’t show the same efficiency in all industries.

In fact, adding too many visuals can distract readers from the core message which often leads to having your call-to-actions ignored.

If you want to get a clear idea on whether or not images are adapted to your email marketing efforts, just try to run a Version A with no visuals (but the same subject line, body and CTAs) versus a Version B that contains visuals: you’ll see which one performs better.

Getting more personal

Adopting a friendlier, more casual tone and copy can often transform the way your readers perceive your email activities.

The copy

While there is no secret recipe to writing perfect copy (because it depends on your objectives), try running different versions through A/B tests while only changing the copy: this could lead to tremendous changes for your conversion rate.

If you’ve formulated different hypotheses about your readers’ expectations, create two different copies based on anticipated behaviors and send them to the same mailing list to see which one outperforms the other.

The best practices for email A/B testing

Now that we covered the main elements that can be tested through email A/B testing, let’s have a quick look at the 4 best practices to bear in mind before running email A/B tests.

Having a goal in mind

Defining objectives prior to running any A/B tests is a massive time-saver for any marketer.

In fact, it’s highly important that we as marketers formulate hypotheses based on the data we exploit.

You need to increase the open rate:In this case, you should mainly focus on your subject lines and preheaders: these are the two main elements that will affect this metric.

You need to increase your click-through-rate, downloads or subscriptions:If you want to increase engagement, then test all body-related content such as the copy, the tone, the visuals and the call-to-actions as they may all trigger an increase in clicks, subscriptions or purchases.

One vs Multiple Variables Testing

When it comes to A/B testing, adding multiple variables in your tests means that you will need an ever-increasing sample size in order to get statistically relevant results.

Besides, comparing two versions with multiple variants each will make it difficult for you to get relevant results as you won’t know which element triggered an increase or a decrease for your key metric.

If you have a small sample size, our general advice is to test one variable at a time.

However, there are cases where you will want to A/B test two completely different versions of your email: you can do so easily as the “winner” could be used for future benchmarks or as a template for your next A/B tests.

Testing at the same time vs testing at different times

Although you can absolutely A/B test your emails based on sending days and hours, try to avoid sending variants at different times: you won’t know if the changes were caused by the time or the email content.

Anthony BrebionAnthony is a B2B Digital Marketing Specialist. He's currently managing Demand Generation at AB Tasty, with a strong focus on marketing automation, nurturing and inbound marketing. He was previously an SEO consultant and worked several years for digital ad houses. View profile on LinkedIn.